Some are tutorial in nature, others are more like a tutorial/reference, and others contain philosophy in addition to tutorial. In some of these references, there is a sense you have programmed in Java previously, and I sense, and it is not directly implied, that the reader has dabbled in a Lisp dialect.

My Ah Hah! moment came recently when I realized that until a couple of years ago, the last languages I used in the commercial world were C++, Java 2, and Perl. Functional Programming (FP) was an academic subject, and though I had heard of Python, there was no pressing reason for me to learn it, at least back then. These books are written by authors with mostly a different programming learning and implementation environments.

So, as I work my way through Clojure In Action and Code Lesson’s Intro to Clojure, there are additional things for me to learn, the biggest of these the differing implementation environments and curriculum from when I started programming.